US2878992A - Centrifuge apparatus and rotor therefor - Google Patents

Description

March 24, I959 E. G. PICKELS EIAL I 2,373,992

' CENTRIFUGE APPARATUS AND ROTOR THEREFOR Filed Dec. 28, 1956 3 Sheets-Sheet 1 IE'IEI E: ff/W K w wan-1 March 24, 1959 a. PICKELS EI'AL CENTRIFUGE' APPARATUS AND'ROTOR THEREFOR s Sheet-Sheet 2 Filed Dec. 28, 1956 IE"IE INVENTORS PIC e/s Jr 5%: W 4770/?636' FIE- 5 Sheets-Sheet 3 a a a w 0 I I 2 w H H ow 7 March 19519 I XE. G. PICKELS El'AL CENTRIFUGE APPARATUS AND ROTOR THEREFOR Filed Dec 2a, 1956 IE'II'5 E1 Edward G. Pickels, Atherton, Richard C. Stallman',San -Carlos,and Philip F. Scofield, Atherton, Califl, as-

signors to Beckman Instruments, Inc., Fullerton, Calif.,

; La corporation of California l V Application December 28, 1956, Serial No. 631,163

1 a 8Claims. Cl. 233-11 This invention relates generally to a centrifuge. ap-, paratus and rotor therefor and more particularly to a high speed centrifuge apparatusof the above character in which the temperature of the rotor is maintained near the outside temperature. c c

i It is ageneral object of the present invention .to pro vide a centrifuge apparatus in which the rotor is mainthat of the outside air by tained at a temperature near insulating the outer periphery of the rotor and'circulating outsideair through the center of the rotor'.

It is another object of the present invention to provide an ultracentrifuge in which means are carried by the United States Patent i i has an opening 20 directly over the rotor.

the housing. I in conjunction with the release knob rotor for circulating outside air through the rotor and the rotor chamber. It is a further object of the present invention to pro vide an ultracentrifuge apparatus in which the rotor has a relatively small axial opening through which outside air is circulatedto effect a heat exchange with the rotor and maintain the same at a temperature near that of the outside air.

Itv is another object of the present invention to provide an ultracentrifuge apparatus in which the rotor has an axial opening and means is of the same which serves to and about the rotor to maintain the same at a temperature near that of the outside air. It is a further object of the present invention to provide an ultracentrifuge rotor which includes a relatively small axial hole formed therethrough having cooling fins and a centrifugal pump mounted on the bottom of the rotor and serving opening, and in which the external surfaces of the rotor are covered with insulating material whereby conduction ofheat, generated by the friction of the surrounding air against the external surfaces of the rotor, into the body of the rotor is reducedby the insulating layer.

These and other objects of the invention will become more clearly apparent frorn'the following description takenin coniunctionwith the accompanying drawing. Referring to the drawing: c I Figure 1 is a perspective view showing anultracentrifuge incorporating the present invention;

Figure 2 is a plan view partly in section of the apparatus of Figure l;

ofFigure 2;

Figure 4 is an enlarged plan view of a typical rotor;

Figure 5 is a sectional view taken along the line 5-5 of Figure 4; and V Figure 6 is a sectional view taken along the line 6-6 of Figure 5.

-The centrifuge apparatus illustrated in the drawing comprises an outer housing 11 which serves to house the working parts. panel of thehousing. They include the coverrelease knob 12,the circuit breaker reset knob 13, the start and stop switch 14 and a timer control 16.

The top of the to circulate outside air through the' The controls are mounted on the 'front' housing is provided with an opening mounted on the bottom circulate outside air through to form the axial opening 2,878,992 Patented Mar. 24,

ice

which the rotor may be installed and removed. A sliding door 18 serves to cover the hole. The door 18 is formed with an opening, preferably louvered, as will be presently described, through which air may circulate; The covered box 19 provides means for storing speed change gears and belts.

Referring particularly to Figure 3,

17 through the door or panel The opening isprovided with a plurality of louvers 21 through which the air circulates, as indicated by the arrows 22. The opening is preferably of restricted size whereby most of the air which circulates downwardly through the same, as will be presently described, is directed downwardly through the center of the rotor. The door has spaced. rollers 23 mounted on each edge thereof. The rollers ride inthe guiding channel 24 secured to the sides of A latch. mechanism (not shown) works '12 to release the panel to provide access to the rotor chamber.

The rotor is operated within the cylindrical chamber 26 which acts as a guard in the event of breaking or explosion of the rotor under the strains occasioned at the high operating. speeds at which it operates. Similarly, the louvers are so formed that if such breakage should occur, none of the parts will fly out through the top and damage surrounding equipment or injure personnel. The cylindricalchamber 26 is mounted on the base 27 by a plurality of pins 28 whichare suitably secured to the bottom thereof, in the bottom, and threading the same as indicated at 29. The pins serve to hold the bottom edge of the cylinder 26 above the base 27, whereby air may circulate out through the opening formed between the base and cylinder. Thus, the air circulates downward through the door, through the rotor and outward through the space formed between the bottom edge of the cylinder 26 and the base 27 as indicated by the arrows 31. p

The rotor 32, to be presently described in detail, is mounted on the end of the flexible shaft 33. The bottom end 'of the shaft 33 is tapered (Figure 5) and vis adapted to fit into the taper formed in the shaft .34. The

bearing'35is mounted on the shaft'34 and is adapted to fit against the shoulder 36 formed in the housing37. The snap-in washer 38 serves the shoulder 36. The bearing hub 39 is secured to shaft 34 and is locked screw 41. The lower end of the v 42. The end portion rides in the bushing 44 and is provided with the spiralgrooves 46 which communicate insideof the housing. When tated at high speeds, the helical grooves serve to pump forced through the openings oil strikes the bearing and serves the same. The upper portion .of the chamber 37a is suitably secured to thelower portion 37b which includes Figure 3 is a sectional view taken along the line 3-3 I engaged by the belt 57 (Figure 3) is'removed and the gear an the bushing by means of screws 53. An O-ring 54 serves to form a suitable seal. The plug 55 provides means for filling the chamber 48.

A gear 56 is mounted on thehub. The gear 56 suitable constant speed motor 58. on the base 27 as,

The motor is mounted as for example by forming a hole;

to retain the bearing against the to the same by means of the. shaft .34 is drilled out through the openings 47 withthe the shaft 34 is being ro- 48 downward. The oil.

which is driven by a Y for example, by meansof the bracket 59. To change speeds the plate 61 which is attached to the base 27 and which is accessible through the chamber suitable driving speed.

d belt replaced to givethe I Referring now more particularly to Figures 4am 5,

a novel rotor is shown.

block 66 ofsubstantially frusto-conical form. The bloclg The rotor comprises a metal includes a plurality of cavities or wells 67 extending from the upper end of the block to a the block and converge in the directhe rotor. A coating of insulating material 68 is formed on the outside-of-the block. The coating may, for example, be an epoxy plastic which is added by dipping the rotor in the liquid plastic. to dipping the rotor in the epoxy solution lid or cover is held over the top of the rotor by the nut 87 Which is threaded at 88 to the rotor. to funnel the air into the n operation, the test tubes having the mixture to be 18 required for the apparatus to come up to speed. As speed, outside air is pumped down through the opening 20 bythe action of the .pump rotor. Most of the air circu ates down outside as previously described, the opening .720 is through-the same'flows'through the rotor with very little spilling over the sides. This reduces the drag on the rotor and permits higher rotative speeds. This also serves to reduce the frictional heat generated at the outside surface of the rotor.

were formed in the block and were equally spaced. The rotor ,had an insulating layer. of epoxy-versamid inch thick on the outer surface. The central opening 69 was 2 inches in diameter' with the'fin assembly having an inside member /8 inchin diameter and was provided with 6 blades.

The rotor was operated at rotative speeds of 24,500 r.p.m. and the temperature rise was found to be 4.5 C. above the outside air temperature of 23.0 C. 'For coma standard rotor which-was not insulated and in WhlCh air cooling means was not provided was tested. It operated at a temperature which was 13" C. above the air temperature air temperatures. The novel apparatus greatly reduced temperature rise of the rotor.

heat generated between the rotor and the surrounding air. circulating outside air down through the center of the rotor.

We claim:

11. In a centrifuge apparatus, a chamber having an opening in the bottom region thereof, a cover having an and serving to close said cham opening formed therein her, a centrifuge rotor assembly and outward through said bottom opening, said; air serving to maintain the temperature of therotorrnear -that of the outside air.

. 2. Apparatus as in claim 1 wherein said means. for circulating outside air throughthe cover and rotor comrotate with the rotor.

v3. Apparatus as in claim ried by the bottom of the rotor.

4. Apparatus as in claim 1 wherein a heat tain the temperature of the rotor air.

with the same rotative speeds and operates with" Means are provided for 2 wherein the impeller is car 8. A centrifuge apparatus as in claim 7 in which said chamber cover is movable to open and close the chamber, and in which the cover opening is louvered.

5 References Cited in the file of this patent UNITED STATES PATENTS Patterson June 16, 1903 Hall Feb. 9, 1926 Allen Jan. 11, 1955

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