US2202157A - Centrifuge - Google Patents

Description

H. G. LEVY CENTHIFUGE May 28, 1940.

Filed June 30, 1937 INVENTOR. //?/72*/' (i. 1 @1/9 621 IB B ATTORNEY.

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Patented May 28, 1940 UNITED STATES PATENT OFFIcE Henri G. Levy, San Francisco, Calif.

' Application June 30, 1937, Serial No. 151,212

4 Claims.

This invention relates generally to centrifuges of the type used in clinical and chemical laboratories, for the purpose of subjecting small confined samples of material tocentrifugal force.

It is an object of the invention to provide a centrifuge of the above character which can be operated at the requisite speed without undue noise or vibration, such as is characteristic of centrifuges of conventional design.

It is a further object of the invention to provide a centrifuge of the above character which will be so constructed as to minimize spill of liquid from the various individual containers, and which will not require careful balancing'of the samples.

Another object of the invention is to provide a centrifuge in which undue temperature rise, due to the beating or threshing action of the sampler tubes in surrounding air, is avoided.

Another object of the invention is to provide a centrifuge of relatively simple construction which can be operated by any ordinary physician or laboratory assistant, without undue skill, and

without personal danger.

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

Referring to the drawing:

Fig. l is a plan View, showing a centrifuge incorporating the presentinvention.

Fig. 2 is a side elevational View of the centrifuge illustrated in Fig. 1, and taken as a crossseotion along the line 2-2 of Fig, 1.

The centrifuge illustrated in the drawing consists of a head Ii), which in this instance is directly mounted upon the vertical shaft ll of an electric motor I 2.

This motor can be of the single phase alternating current induction type, having a normal speed or operation comparable to that desired in the centrifuge, as for example a speed of 3500 R. P. M. It is shown carried by a suitable supporting base l3, which also forms the main base for the machine.

Attached to the head in and circumferentially spaced apart, are the holders I4, which in turn are adapted to receive the individual sample tubes I 6.

In a typical instance each of the holdto positions in a common horizontal plane.

The

sampler tubes fit snugly within the holders l4, and when the machine is in operation, are firmly retained within the holders by centrifugal force.

The head Ill also carries a sheet metal housing designated generally at 22. This housing is circularly contoured as'viewed in plan, and the top wall 23 is fiat. The lower wall is formed of a portion 24a, conforming generally to the surface of a sphere, and a connected portion 24b conforming generally to the surface of a truncated cone. Both the upper and lower walls of the housing are firmly secured to the annular portions 26 and 27 of the head Iii, as by means of screws 28 and 29.

Secured to the peripheral portion of the housing described above, there is a metal band 3! which has considerable weight, and which imparts a fiy-wheel'efiect as will'be presently described. In practice the peripheral edge portion 32 of the top wall 23, can be bent about the ring 3|, to afford a firm attachment. The wall portion 24a of the housing has an out-turned edge 33 on its periphery, which is retained upon the inner periphery of the ring 3!. Thus the ring 3| is held in place by the flat wall 23, and when the machine ,is in operation centrifugal force created in the band is taken up by tension along the band itself.

In order to facilitate introduction and removal of the sampler tubes or containers It, the top wall 23 of the housing is provided with a plurality of circumferentially spaced openings 34. When the holders hang downwardly in the position' illustrated in Fig. 2, the open ends of the sampler tubes l6 project a small amount through the openings 34. However, when the head II] is in rotation and the holders are swung outwardly to a horizontal plane, the holders and also the containers or sampler tubes, are entirely within the confines of the housing.

While my centrifuge. has sufficient inherent strength to avoid mechanical failure when properly operated, it is desirable to provide guard means to protect persons in the proximity of the machine, in the event of possible failure. For this purpose I have shown a guard band 36, which surrounds the periphery of the housing. This guard band is supported by suitable arms 31, from the base of the machine.

Operation of my machine can now be reviewed as follows: Samples to be subjected to centrifugal force are placed within the sampler tubes or containers l6, and these tubes or containers are then inserted in the holders l4. Current is now applied to the motor [2, to start the head in rotation. As the machine gains speed the holders l4 swing outwardly to positions in a horizontal plane, as indicated by dotted lines in Fig. 2. Since the housing rotates together with the holders and the sampler tubes, the air confined by the housing likewise rotates, to eliminate or minimize all air turbulence surrounding the holders. Thus there is a negligible amount of heating of the samples due to creation of turbulent air currents, as is common with prior types of centrifuges. There will also be a minimum amount of noise produced, due to the absence of turbulent air currents or beating action of the holder-sin the air. After the machine has operated for a prescribed period of time the current to the motor is interrupted, and as the head ceases to rotate the holders drop down to the general upright position illustrated in Fig. 2, to avoid any spill of the contents and to permit ready removal of the sample containers.

The presence of the weighted band 3! serves two useful functions. The fly-wheel effect which it necessarily occasions prevents abrupt starting movement, such as might otherwise be produced by a direct connected electric motor. 'The absence of such abrupt movement minimizes spill from the sampler tubes. The second effect accomplished is to so distribute the weight of the rotating parts, that poor distribution of samples in the various holders, will have little if any effect upon proper operation of the machine. In other words it is possible with my machine to have one sample tube on one side of the head filled with liquid, and the tube upon the other side of the head missing or empty. With many machines this would produce such a degree of unbalance as to cause mechanical failure due to extreme vibration when the machine is in operation. With my machine the unbalance produced causes little if any appreciable vibration of the machine. This is attributed to the manner in which the band 3| concentrates weight at the periphery of the rotating parts, thereby making it impossible to materially unbalance the machine 1- by variations in weighting nearer the center of rotation, corresponding for example to samples of different sizes.

I claim:

1. In a centrifuge of the character described, a-head mounted for rotation about a vertical axis, a plurality of holders secured to said head and adapted to receive individual containers, said holders being pivotallysecured to the head whereby the containers assume a generally upright position when the head is stationary and swing outwardly to a common horizontal plane when the head is rotated, a circularly contoured housing fixed to rotate with the head and having upper and lower sides extending generally above and below said holders and said containers for both generally upright and horizontal positions of the same, said housing being formed to entirely en- 'close the container for horizontal position of the same, the upper wall of said housing being provided with openings to permit introduction and removal of containers-with respect to the holders, saidopenings being formed above the regions of said pivotal connections.

2. In a centrifuge, a head mounted for rotation about a vertical axis, a plurality of circumferentially spaced holders secured to said head and adapted to receive individual containers, said holders being pivotally connected to the head whereby the containers assume a generally upright position when the head is stationary and swing outwardly to a common horizontal plane when the head is rotated, a sheet metal housing fixed to the head and serving to enclose the holders and said containers when the centrifuge is in normal operation, the housing also serving to generally embrace the holders when the head is stationary, the upper wall of said housing having circumferentially spaced openings disposed above the regions of the pivotal connections and in registry with the holders when the head is stationary, and a weighted rim secured to said housing and serving to impart a fly-wheel efi'ect to the centrifuge.

3. In a centrifuge of the character described, a head mounted for rotation about a vertical 'axisya plurality of holders secured to circumferentially spaced points on the head, said holders being pivotally secured to the head and being adapted to receive individual sample tubes, whereby the sample tubes normally assume a generally upright position when the head is stationary but swing outwardly when the head is rotated, a circularly contoured sheet metal housing fixed to the head, the housing serving to enclose the holders and said tubes when the centrifuge is in normal operation, and also serving to generally embrace the holders when the head is stationary, a weighted metal band secured to the periphery of said housing and serving to impart a fly-wheel elfect to the same, and a stationary guard ring surrounding said band and spaced radially from the same.

4. In a centrifuge, a head mounted for rotation about a vertical axis, a plurality of holders secured to the head and adapted to receive individual containers, said holders being pivotally secured to the head, whereby the containers assumea generally upright position when the head is stationary but swing outwardly when the head is rotating, a housing fixed to the head and serving to enclose the holders and said containers whenthe centrifuge is in normal operation, the lower side of said housing consisting of a generally spherical shaped portion joined to a downwardly divergent frustrated conical shaped portion, whereby said holders are embraced by the housing when the head is stationary,the upper wall of said housing being substantially planar and having circumferentially spaced openings in the same to register with the holders when the head is stationary and to facilitate introduction and removal of said containers with respect to the holders, and a weighted ring secured to that peripheral portion of the housing adjacent the top wall.

HENRI G. LEVY.

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