US2838954A - Precession control means for upright centrifugal spinner - Google Patents

Description

June 17, 1958 F. R. HlGLEY PRECESSION CONTROL MEANS FOR UPRIGHT CENTRIFUGAL SPINNER Filed Feb. 21, 1952 M/myg United States Patent PRECESSION CONTROL MEANS FOR UPRIGHT CENTRIFUGAL SPINNER Frank R. Higley, Cleveland Heights, hio Application February 21, 1952, Serial No. 272,873

1 Claim. c1. 74-513 This invention relates ,to spinning devices of the type adapted to spin erectly about an upright axis while supported from below itscenter of mass and whiledriven at spinning speed. Examples ,of such a device areunderdriven centrifuges, extractors, etc.

A principal object of the invention is to reduce pre- K quick deceleration of the device with minimum 'precessional motion.

Thus, in general, the invention, as applied to a centrifuge, permits higher speed and consequently shortened centrifuging period per se, plus faster and smoother deceleration, thus still further shortening the operating cycle which includes spinning as well as deceleration therefrom to rest.

Still another object is to accomplish the above objects with expenditure of the minimum possible energy.

Briefly, the invention is based on the principle of reducing precession by forces applied to the spinner concentric of its precessional axis, responsive to and in the direction of any precession of the spinnerelfectively independent of the rotational drive of the spinner about its own axis. Thus, instantaneously, the unit precessionreducing force is applied in a direction tangent to and with the precessional motion and proportional thereto. The total force therefore may be considered as one in torque about the precessional axis, as distinguished from the actual or geometrical axis of rotation, acting in torque in the direction of precession and proportional thereto By gyroscopic principles such forces are effective toreduce the radius of any precession to zero and thereafter maintain spinning without precession during spinning speed. I

As another object of the invention and as appears here inafter, the invention provides support, drive, and correction of precession, all through the cooperation of a single pair of surfaces.

Further objects of the invention will be apparent from the following description taken in connection with the accompanying drawings, which are conventionalized views, in elevation and somewhat diagrammatic, with parts broken away to show details of construction, wherem- The drawing shows a simplified elementary form of the invention illustrative of its principles.

Parts appear as in spinning operation, that is, with the axis of the spinning device vertically disposed, as were its geometrical and physical axes coincident with each other, and also with the axis about which precession would occur were there any precession-it being understood that by the invention precession is reducible practically to absolute zero.

The spinner device indicated is in the form of a centrifugal extractor having a basket 1 secured on the spindle 2 and having a footing 3, it being understood that these 2,838,954 Patented 'June 17, 1958 three parts of the device are rigidly secured together and so proportioned as to permit spinning operation thereof as a unit. Drive means having a vertical axis capable of revolution at spinning speed is provided for the device, such drive means being here indicated as in the form of an electric motor 4 having a vertical shaft 5, to which shaft is secured a member 6 on which the footing 3 of the spinner device rests for support and drive.

' The motor 4 issecured on a base or frame 7 which includes an arm 8 adjacent the basket 1 having an opening'9, concentric with the shaft 5 and somewhat enlarged the spinner device. The surfaces are so arranged as to areaycoefiicient of friction and curvature radius, with respect to the weight of the spinner device, that the device may be driven at spinning speed by torque transmitted between the surfaces; and preferably also to permit some slip between the surfaces, particularly at the commencement of acceleration from rest, to provide the characteristics of a slip clutch as Well known in the art.

In operation, commencing with the parts positioned as shown, with the spinning device being driven at high spinning speed by the motor, it will be apparent that the axis of the spinner device is vertical and in alignment with the axis of the driving shaft 5, for simplicity it being here assumed that the spinner device itself is in perfectstatic and dynamic balance about its geometric axis, which latter therefore coincides with its physical axis.

All driving torque is transmitted to the spinner device by way of the described cooperative friction faces of the parts 3 and 6.

Suppose now, due to sudden unbalance or other superimposed load conditions, the spinner device is caused to tilt and thereby displace its axis laterally from the position shown, such tilting would necessarily be about the point A and would cause lateral displacement of the footing 3 on the member 6, with eccentricity of the footing relative to the member 6.

The spinner would precess in the direction of its rotation, due to the force of gravity acting according to known gyroscopic principles.

But the member 6 would exert a force upon the member 3 eccentric thereof and in the direction of precession-and this in addition to the torque by which the spinning device is driven on its own axis. Such additional force is effective on the spinner device as torque responsive to and in the direction of precession, and concentric about the axis of precession. By known gyroscopic principles such force is effective to reduce the precession, ultimately to Zero. The greater the precessional radius the greater the effect of gravity toward increasing the precession, but the greater the eccentricity just described, and the power which reduces, and ultimately eliminates, the precession.

For quick deceleration of the spinner device after accomplishment of the purpose of its spinning, it is provided with brake means acting directly thereon, as distinguished from operating through the frictional bearing between the members 3 and 6. As here shown for the purpose, the member 3 is provided with a flange 10 adapted to serve as a brake operable upon by braking forces here conventionally indicated by the arrow B.

Upon application of such braking forces to the spinner device, coincident with deenergization of the motor 4, the member 6, by its inertia and that of the motor rotor parts with which it is secured, will tend to overrun the spinning device. Therefore. at the cooperative bearing faces of. the parts 3 and 6., torque will be continued and in the same direction, and consequently the precessionreducing action will be maintained generally the same as the spinning device is decelerated.

The spinning device wilb eventually become;v unstable and consequently nutate under gravity within the limit permitted by the size of the opening, 9, and ultimately come. to rest in a tilted position.

Advantage of such tilt may be takenin some applica tions of: the invention, as to provide thereby easier access to the top of the basket 1-, when. in rest.

The described precession control, is had with. the expenditure of energy only sufficient for the-necessary precession-reducing function. When the. spinner device is in operation without precession, all principal rotating parts being then concentric,substantially no energy whatsoever is consumed in recession control. p

In the arrangement illustrated the curvature of the cooperating friction surfaces which together determine the center A of precession are upwardly convex sothat the center is below them. They could, if preferred, be-made upwardly concave so that the center would be above them, the necessary conditioninthis respect being merely 5 that the center of precession be below the center of gravity of the rotating mass.

I claim:

In combination with a device adapted to. spin. erectly,

a driving member rotatable on an upright axis,,said, de- 1 vice and said driving member having cooperative bear- "ing faces through which said device is mounted on said member for support and frictional spinning drive, said bearing faces being formed to provide a point in said axis located below the center of mass of said device and about which the device may have precession accompanied by slippage between said faces while being spun by said driving member, whereby said precession will be accompanied by torque components at said faces eifective toward diminishment of said precession, and brake means arranged to be applicable to said device independent of said driving member, whereby said torque components may be continued during deceleration of said device by said brake means.

References Cited in the file of this patent UNITED STATES PATENTS 330,345 Nielson et a1. Nov. 10, 1885 996,776 Lawson July 4, 1911 1,311,150 Hebrard July 29, 1919 1,834,829 Ditzler Dec. 1, 1931 1,857,736 Morrison May 10, 1932 1,975,740 Brown Oct. 2, 1934 2,033,146 Motycka Mar. 10, 1936 2,137,540 Motycka Nov. 22, 1938 2,350,218 De Remer May 30, 1944 2,353,150 Dietz July 11, 1944 v FOREIGN PATENTS 509,447 France Aug. 18, 1920 Great Britain Apr. 15, 1937

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