US2681166A - Vacuum chamber closure construction - Google Patents

Description

June 15, 1954 P. F. SCOFIELD 2,681,166

VACUUM CHAMBER CLOSURE CONSTRUCTION Filed May 22, 1950 I 2 Sheets-Sheet l 'INVENTOR.

ATTORNEYS June 15, 1954 P. F. SCOFIELD 2,681,166

VACUUM CHAMBER CLOSURE CONSTRUCTION Filed May 22, 19 50 2 Sheets-Sheet 2 F /7 24 /4 7} PIEL-L I Patented June 15, 1954 VACUUM CHAMBER CLOSURE CONSTRUCTION Philip F. Scofield, Atherton, Calif., assignor to Specialized Instruments Corporation, Belmont, Califi, a corporation of California Application May 22, 1950, Serial No. 163,533

1 Claim. 1

This invention relates generally to the construction of vacuum chambers suitable for housing centrifuge rotors.

In the construction of ultracentrifuges, which may employ rotor speeds ranging from 5,000 to 70,000 R. P. M., it is essential that the rotor during operation be housed in a chamber which can be evacuated, and which is capable of withstanding explosion of the rotor. Since the chamber is a permanent part of the machine, it is necessary to facilitate access to the interior of the chamber for the insertion and removal of rotors. Conventional sealed tank covers are not satisfactory for this purpose because of the difficulties involved in applying and loosening the clamping devices employed.

It is an object of the present invention to provide a vacuum chamber construction suitable for housing centrifuge rotors which will minimize the effort and time required for opening and closing the chamber.

Another object of the invention is to provide a vacuum chamber construction of the above character in which the cover will have adequate strength to withstand severe vertical impacts.

It is a further object of the invention to provide a novel construction of the above character which makes use of a resilient seal ring having sealed contact between the cover and the chamber, and which is engaged with both these parts only for the closed position of the cover.

Another object of the invention is to provide a sealed cover construction for a vacuum chamber which greatly facilitates operator control from the front of the machine, as by turning a single manually operated member.

Further objects of the invention will appear from the following description in which the preferred embodiment has been set forth in detail in conjunction with the accompanying drawing.

Referring to the drawing:

Figure 1 is a plan view illustrating a vacuum chamber construction incorporating the present invention.

Figure 2 is a cross-sectional detail in side elevation and taken along the line 2-2 of Figure 1.

Figure 3 is a cross-sectional detail taken along the line 33 of Figure 2.

Figure 4 is a cross-sectional detail taken along the line t4 of Figure 1.

Figure 5 is a cross-sectional detail taken along the line 5-5 of Figure 1.

The vacuum chamber illustrated in the drawing consists generally of the side walls [0, which can be formed cylindrical, together with the bottom wall II. The top plates 12 and I 3 can b substantially square as shown in Figure 1, and they are provided with the aligned openings l4 and IE to facilitate access to the interior of the chamber. At the forward side of the chamber the plates l2 and I3 are separated by the spacer bar [6, and along the sides of the chamber these plates are separated by the rearwardly extending spacers i1. Spacers H can be fabricated from two small structural angles welded together as illustrated. The assembly just described is clamped downwardly upon the upper edge of the side Walls ill, by clamping bolts I 8. It will be noted that the lower ends of these clamping bolts are welded to the side walls I 0. They are proportioned and designed to withstand great vertical forces.

Suitable means is employed for establishing a good vacuum seal between the plate [3 and the upper edge of the side walls 10. Thus an annular recess [9 is provided which serves to accommodate the resilient O ring 20, whic his made of suitable material such as synthetic rubber. N ormally the 0 ring is slightly compressed whereby it maintains an effective vacuum seal.

Various parts (forming no part of the present invention) can be housed within the vacuum chamber. Thus a heavy guard ring 2| can be located within the side walls H, and within the heavy guard ring 2| there may be a light container or liner 22. The centrifuge rotor 23 is coupled to a drive shaft extending upwardly through the bottom of the vacuum chamber, as disclosed and claimed in copending application Serial No. 163,393, filed May 22, 1950, in the name of G. Pickels, and entitled Centrifuge Apparatus.

A relatively heavy cover plat 24 is disposed between the plates l2 and i 3, and is adapted to slide horizontally between open and closed positions. It is preferably rectangular or square in contour, as illustrated in Figure 1 and is of ample size to extend completely over the opening l4. Rollers 25 and 26 are mounted on one edge of the plate 2% (see Figures 1 and 2) at points adjacent the forward and rear corners. An additional roller 27 ismounted upon the other side edge of the plate, and is intermediate the forward and rear corners. Extending rearwardly from the plate l3, and attached to the rear ends of th spacers l1, are the extensions 3|, which provide vertical guide ribs 32 and trackway surfaces 33 which are on an elevation corresponding to the top surface of the plate !3. When the cover plate 24 is moved rearwardly toward open position, the rollers 25, 26 and 2? ride along the track surfaces 33.

The upper face of the plate I3 is provided with a circularly contoured groove 34 which serves to be understood that the resilient ring in expanded position extends above the upper surface of the plate l3. However when the cover plate 2s drops lown upon the 0 ring, the O ring establishes sufficient vacuum sealing contact with both the cover and the plate l3 to maintain a differential pressure on the cover when evacuation of the chamber is commenced. Such initial differential pressure urges the cover into metal to metal contact with the plate l3 and to compress the O ring to thereby establish a good vacuum seal. When the cover is moved toward open position the rollers are moved out of the recesses 3?, 36 and 33, thus elevating the cover 26 out of contact with the resilient 0 ring 36.

Suitable manually operated means is provided for moving the cover between open and closed positions. A desirable means for this purpose consists of a manually rotatable member 41 in the form of an operating knob, which is located adjacent the front side of the chamber. This knob is mounted on the forward end of a shaft 42, which is journaled in the stationary support brackets 46, 43. A cable winding drum id is disposed concentric with the knob 4| and shaft 62, and is splined to the knob by the pins it. Adjacent the drum Mi the shaft 42 extends through the stationary threaded sleeve ll, and this sleeve has threaded engagement with the drum 66. Upon rotation of the knob 6| the drum 44 is rotated, and is simultaneously caused to move longitudinally by virtue of its threaded engagement with the sleeve 41. A pull cable or cord 49 is anchored to and wound about the drum 44. One extended end of this cable engages over the forward and rear sheaves i and 52, and is anchored at 53 to the rear corner of the cover plate. The other length of the cable extends over the forward sheave 5 3, and is anchored at 56 to the adjacent forward corner of the cover plate. It will be evident that with this arrangement rotation of the drum 14 applies forces to the cover plate to move the same between open and closed positions. Movement of the plate to full closed position can be checked by use of a rubber cushion 51, which is carried by the spacer bar i6 in position to be engaged by the forward edge of the cover plate.

Operation of the chamber construction described above is as follows: After a rotor has been inserted into the vacuum chamber, the operator turns the knob 4| whereby the pull cable 65! moves the cover plate 24 to full closed position. During the major part of this movement the cover plate is elevated out of contact with the resilient O ring 36. When the cover plate reaches substantially full closed position the rollers 25, 26 and 2! drop into their corresponding recesses 31, 33 and 39, thus causing the cover to come to rest with its lower face in contact with the resilient 0 ring 36. After initial evacuation of the chamber to provide a differential pressure on the cover, the chamber is sealed to enable maintenance of a proper vacuum. At the end of the run and after the chamber has been vented to the atmosphere, the operator turns the knob 4| in an opposite direction whereby the cover is moved back to open position. During the initial part of this movement the rollers 25, 26 and 21 elevate the cover plate out of engagement with the resilient O ring 36, and thereafter the cover moves rearwardly with very little friction to full open position.

It will be evident from the foregoing that I have provided a construction which greatly facilitates opening and closing of the vacuum chamber, while at the same time insuring a proper vacuum seal. No clamping devices are required and the entire operation can be carried out by turning a single manually operated member. The cover is capable of withstanding great vertical forces which may be applied in the event of a rotor explosion, both because of the heavy plate construction employed and the retention of the cover plate between the plates 12 and I3.

I claim:

In a vacuum chamber construction for housing a centrifuge rotor, a chamber comprising side and bottom walls, a horizontal and plate mounted upon the upper end of the side walls and sealed with respect to the same, a groove formed in the upper face of said end plate and embracing the upper access opening of the chamber, a horizontal cover plate disposed to overlie the end plate and movable in a horizontal direction between open outof-the-way and closed positions, a resilient seal ring of the O-ring type accommodated in said groove and adapted to have sealing contact between said plates for closed position of the cover plate, said seal ring in section having a diameter greater than the depth of the groove whereby the ring is compressed in a vertical direction when the cover plate is pressed in metal-to-metal contact with the end plate, means forming extensions of the top plate, rollers secured to the side edges of the closure plate and disposed to track upon the upper face of the end plate adjacent the sides of the chamber and on said extensions, and recesses in the upper face of the end plate and serving to loosely accommodate the rollers when the cover plate is in said closed position, dropping of the rollers in said recesses causing the lower face of the cover plate to contact and to be supported solely by the seal ring, whereby the cover plate is free to press into metal-tometal contact with the end plate when the interior of the chamber is evacuated, initial movement of the cover plate from said closed position toward said out-of-the-way open position serving to displace the rollers from said recesses and to elevate the cover plate out of contact with the seal ring, and means for moving the cover plate between said positions.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 853,168 Garbe May 7, 1907 863,001 Seebeck Aug. 13, 1907 1,795,016 Faber Mar. 3, 1931 1,826,941 LaMont Oct. 13, 1931 1,868,147 Kruse July 19, 1932 2,223,023 Weilemann Nov. 26, 1940 2,330,220 Kemper Sept. 28, 1943 2,370,660 Heineman Mar. 6, 1945 FOREIGN PATENTS I Number Country Date 204,950 Switzerland Aug. 16, 1939

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