US2255799A - Shaker - Google Patents

Description

Sept. 16, 1941. GQH. MEINZER f SHAKER 2 Sheets-Sheet l Filed Aug. 5, 1939 Sept 16, 1941. G. H. MEINZER l 2,255,799

SHAKER Filed Aug. 5, 1939 2 Sheets-Sheet 2 45 54 '35 33 43 45 46 16 JZ 4@ g 4 n .r

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the pivotal joint between the spring and thev by a circular web 32.

The use of table frame makes of the spring a true pendulum whose amplitude may be changed without affecting materially its rate of oscillation.

Thus the table is supported for free rectilinear oscillation in one direction only and the period of oscillation is determined by the dimensions and elastic constants of the supporting springs. By this construction, once the table is deflected, a

rate of oscillation follows 'which is independent,

of the mass of the oscillating system and it recarries in order to maintain the amplitude constantrfor all Kahn tests regardless of -the numberof test tubes carried by the shaker at any given' Y v y l .v i'isthen'secured in place. The top comprises a of oscillation andv Q' anges 43 which serves as side rails and dependtime. v

In regulating the amplitude the action of the table, 'the short spring blades l1 Vand VI9 are provided upon' both sides of the longer blades I3 to establish a modulus of operation which opposes any tendency of increased load to'change the action of the table.

The shorter springs I'l and I9 operate at all times to provide a cri'sp action of the table when it oscillates, whether the load be heavy or light; L

This crispness oi' action is substantially constant for all'loads` because the added momentum factor of heavier loads is directly opposed by a proportional increase of tension inthe flexV 'of th'e short springs. i Thus', Vvfor any increase vin load, only.v sufcient deflecting force need be applied to' ther' table tobring the amplitude of oscillation up to i the limits I3 and I4. v

Although it will be noted that the amplitude of oscillation'is a' balancing of twofactors, namely, loadand deflecting force, and thatithe amplitude of oscillation can be varied for any given deilecting force by varyingk the load, the relationship of these two factorsin providing .a machine Y.

for'perflorming the shaking operation in Kahn of the Vdeilecting force and regulation-ofthe deflecting force does not change theperiod of Yoscillation.

The unit by which the deiiecting'force is gen- 4| Vand the resistance 42 connected in series therewith.

The offset or eccentricity and the weight of the flywheel 34 as a rotating mass, are so de- 5 signed that within the power supplied to the motor, the deilecting impulses of the flywheel keep in step with the natural period of oscillation of the system. By way of example, the eiective eccentric action of the flywheel should be l0 close tothe moments of inertia oi the table, it being better to have the flywheel action more than enough for this purpose than too little.

lWith it too little, the flywheel will cause the table 'ntovibrate rather than oscillate.

The motor is first secured in place on the table'and then the ywheel 34 is mounted and adjusted asV to height. The top I2 of the table stamped aluminum plateV having upstanding side ing.V end -angese 44A which protect theV endsY of place with L-shaped endbrackets 41 adjustable thereby to serve as end rails for trays (not shown) placed vupon he table. The shaker shown laccommodates two trays of test tubes and two upstanding `lugs tween them. T

upon the table, the switch 40 isturned on and the rheostat 4I adjusted to bring the amplitude n of the oscillation up tothe position indicatedL by 'I3 and I4. The center-ofthe eccentric mass 'f37of"the` ywheel driven by the motor describes a path which is approximately an ellipse' whose width is constant.

Referring tothe ellipseas though divided into I nquadrants bounded bythe longest and shortest.

lNfdiameters o f'the'ellipse, and starting with the ywhe'el at the longest diameter, it will be found that for'any cycle the table is deflected VVin the Mwheel with regard tofthe' motor shaft. N' InY the first quadrant thetable is 'movedby the springs toward its opposite position asthe iiywheel moves in the same direction, the reflex action of the springs beingefective.

in the second quadrant to carry the table past the middle point Vof the ellipse to the tablesYV y Y "in the other two quadrants in the opposite dierated is Indicated at 3l where'it is rigidly secured" Y tothe table frame I! on the bottom side thereof wherethe truss `webs V3i) deepen and are joined The circular web defines a flywheel compartment 33 immediately below-1 the plane and inthe center'of the table'where an eccentric flywheel V34 is located and locked to the upper end of the shaft-35 upon a motor 36.' The -lmotor 33 is secured immediately below the j Vflywheel compartment 33 against the bottom face)Y l ofthe floor 3l ofl thecompartment 33 byb'olts 38. With the weight of the motor 36 located below 'I the flywheelccmpartmentandthe load'carrie'd v Y by the table disposed above the'iiywheel comparte v` ment the flywheel is adjusted vertically between 1 thesetwo centers of `mass to balance themv kat l thenormally expected load. v Y The-motor is preferably a series motor whose V torque varies in relation to the impressed voltage l as controlled" by the'main switch 43, the rl'ieostatA Vmfto'flywheel,momentum and in the deceleration quadrant, the momentum` added bythe motor is expended against the inertia of the table and its floadrj" It is during the acceleration quadrant that the motor supplies energy to' the eccentric "mass in relation to the voltage impressed'upon Vit is the limits of the acceleration possiblewithV the Ypower ,output of the motor thatfthe amplitudeofoscillation-of the table can be con- -I yfuelled in relation tothe road upon the table.

heavierfloads'which tend to decrease the ampli-4,

linde .can bewcounteractedfby increasing thf 7""torque output of the motor to accelerate the ec` thetable'frame.' 'Studs 45 locate the tcp and Y Wingnuts 46 are employed to hold the top in 1 48 serve as dividers be- In operation, a tray .ofv ,test tubes is placed same direction as the center of mass of the yl 'During the rst'quadrant, thetorque of the `fmotozr(accelerates the iiywheel. Thereafter the Y momentum'of the ywheel is partially expended the motor by the adjustment of the rheostat and Thus, as the load carried by theY table varies` from time lto `time the moments of inertia of increased .load inertia and bring the amplitude ofthe table 'up tothe .limitation I`3V andv 14.

'The construction shownA and described is thus seen to bea lpendulating one whose period varies but slightly under wide changes of loadas con-f forcein relation to the load merely by varying the resistance in the series motor circuit.

Although the invention has been described in connection with a specific embodiment, the principles involved are susceptible to numerous other applications which will readily occur to persons skilled in the art. Consequently, it will be apparent to those skilled in the art that various uses, modications and changes may be made without departing from the spirit and substance of the invention, the scope of which is commensurate with the appended claims.

What is claimed is:

1. A laboratory shaker for shaking a container approximately at a certain required frequency and a certain required amplitude, comprising an oscillating system including a holder and supporting springs designed to have approximately the desired natural frequency of oscillation with the intended load, a motor forming a rigid part of the oscillating system and having the characteristics of controllable torque and a tendency to reach a speed in excess of said frequency; and a Weight mounted on the system for eccentric rotation, driven by said motor and having sufficient mass with respect to a low controlled torque of the motor and the mass of the oscillating system to retard the speed of the motor approximately to said frequency whereby controlling the torque of the motor will control the amplitude of the oscill-ations substantially without changing their frequency, and means for controlling said torque.

2. A laboratory shaker for shaking a container I approximately at a certain required frequency and a certain required amplitude, comprising an oscillating system including a holder and supporting springs rigid in all directions except for u back and forth movement in one direction and designed to have approximately the desired natural frequency of oscillation with the intended load, a motor forming a rigid part of the oscillating system and having the characteristics of controllable torque and a tendency to reach a speed in excess of said frequency; and a weight mounted on the system for eccentric rotation, driven by said motor and having sufficient mass with respect to a low controlled torque of the motor and the mass of the oscillating system to retard the speed of the motor approximately to said frequency whereby controlling tne torque of the motor will control the amplitude of the oscillations substantially Without changing their frequency, and means for controlling said torque.

3. A shaker for shaking a container, comprising an oscillating system including a holder and supporting springs having a natural frequency of oscillation with a particular load, a motor forming a rigid part of the oscillating system and having the characteristics of controllable torque and a tendency to reach a speed at least as high as said frequency; and a Weight mounted on the system-for eccentric rotation, driven by said motorlandfhaving sufficient mass with respectv toi-'allow controlled torque of the motor and the masso'fthevoscillating system to-'retard the speed o'f the motor -approximately to said frequency whereby controllingY the torque ofthe motorwill control the amplitude of the oscillations sub-v stantially. without changingv the frequency, and means for controlling said torque.

4l. A lshaker comprising an oscillating system including a holder; spring support means for the holder, and a motor, and an eccentric mass driven by the motor of such relative size that the motor may be retarded by it to the natural frequency of oscillation of the -oscillating system, the support means comprising leaf spring members secured to the holder and to a support, and secondary leaf spring members having free moving ends and reinforcing the other leaf spring members against excessive deflection adjacent the points at which they are secured and increasing the stiffness of the spring members to give them a crisp action when they have been deflected by movement of the holder and thus provide a relatively high frequency of oscillation.

5. A laboratory shaker for shaking a container approximately at a certainv required frequency and a certain required amplitude, comprising an oscillating system including a holder and supporting springs designed to have approximately the desired natural frequency of oscillation with the intended load, a motor having the characteristics of controllable torque and a tendency to reach a speed in excess of said frequency; and a weight mounted on the system for eccentric rotation, driven by said motor and having sufficient mass with respect to a low controlled torque of the motor and the mass of the oscillating system to retard the speed of the motor approximately to said frequency whereby controlling the torque of the motor will control the amplitude of the oscillations substantially without changing their frequency, and means for controlling said torque.

6. A laboratory shaker for shaking a container approximately at a certain required -frequency and a certain required amplitude of oscillation, comprising an oscillating system including a holder and yieldable supporting and positioning means including spring means and designed to urge the holder to a given position and to have approximately the desired natural frequency of oscillation with the intended load, a Weight mounted on the system for eccentric rotation,

and a power system including a motor forming a rigid part of the oscillating system and having a rotor in driving relationship with the weight, the motor having a tendency to give the weight a speed in excess of said frequency but the relationship between torque output of the power system during normal running conditions and the mass and eccentricity of the weight and the mass and natural frequency of the oscillating system being such that the speed of the motor remains approximately at said frequency and approximately the required amplitude of oscillation is maintained, and said power system as it is normally started also having a sufficiently low starting torque with respect to the masses so that its speed will not jump beyond the critical speed at which the masses will cease to be able to retard it to the approximate required frequency. y

7. A shaker for shaking a container approxi`- mately at a predetermined frequency, comprising' an oscillating system including a holderandyieldable supporting and positioning means including a spring, urging the holder toward ak given position and having'a natural frequency of oscillationV with a' particular load approxi- 'mately equal 'to saidpredetermined frequency,

trollableV ,torque` and .Lag itendencyi to drive the` Weightv at/a speedgin 'excess ofes'aid frequency, said Weight. havingsucienty mass with respect to the torque of the motor and the-mass of the oscillating system 'toi retardy the speedk of the motor; to 'give. the Weight approximatelyl said frequency Wherebycontrolling the torque ofithe' motor jwill control the amplitude ofjthe.oscilla tions substantially without 'changing' thefre-r 10 quency, A.and meansforcntrolling said torque.

CERTIFICATE CE CORRECTION. Patent No. 2,255,799. september 16, 19in. CCTTHCLD E. MEINZEE.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows Page 5, second column, line 8 and page LL, second column, line 9, claims 5 and 7 Vrespectively, for the article "the" after changing" read --their-'-; and that the said vLetters Patent should be read with this correction therein that the same may conform to the record` of the casev in the Patent Office.

Signed and sealed this i llth day` of November, A. D. 19ML.

Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

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