Mixing apparatus

A mixing device is disclosed for gently agitating the contents of one or more closed containers. The device includes a plurality of cylindrical rollers parallelly juxtaposed and adapted to rotate in an eccentric fashion about respective longitudinal axes that are parallel to each other and inclined to the respective cylindrical axes of the rollers. A drive bar coupling interconnects the rollers and a drive motor so that the rollers rotate in the same direction and at the same speed thereby imparting a simultaneous rocking and rolling motion to the containers when placed in supporting contact with adjacent rollers.

BACKGROUND OF THE INVENTION 
The present invention relates to mixing devices and more particularly to an 
improved apparatus for gently agitating the contents of a plurality of 
closed cylindrical containers by simultaneously rotating and rocking the 
containers. 
In the working environment of the scientific laboratory, researchers and 
technicians utilize a variety of devices to mix or blend the contents of 
test tubes and vials prior to conducting tests or experiments. 
Particularly in the field of hematology, such mixing devices are employed 
to blend blood samples in sealed containers to assure their homogeneity 
before a pathological or other medical examination. One such type of 
hematological mixing device involves the impartation of a gentle rocking 
or see-saw motion to the sealed containers while they are slowly rotated 
so that the samples are thoroughly mixed without frothing or breakdown of 
the blood cells. This type of device generally includes a plurality of 
cylindrical rollers mounted alongside each other having parallel 
cylindrical axes and positively interengaged to rotate in the same 
direction and at the same speed on rotational axes that are parallel to 
each other and angularly disposed to the respectively cylindrical axes so 
that the rollers rotate in an eccentric fashion. 
While existing mixing devices of this type have been successful in properly 
agitating the contents of sealed cylindrical containers for laboratory 
tests and experimentation, such devices have experienced problems in the 
rotational driving and synchronous coupling of the rollers. Gear trains 
have been employed in such mixing devices to drive and couple the rollers, 
but have required precision alignments in their mounting to avoid binding 
and jamming during operation. Furthermore, such alignments have been 
time-consuming and resulted in costlier assemblies. 
SUMMARY OF THE INVENTION 
Accordingly, it is a general purpose and object of the present invention to 
provide an improved mixing apparatus for agitating the contents of 
containers. 
Another object of the present invention is to provide a mixing device that 
thoroughly blends test samples in sealed test tubes and vials. 
A further object of the present invention is to provide a mixer that is 
economical in construction and reliable in performance, not being given to 
jamming or binding in its operation. 
Briefly, these and other objects of the present invention are accomplished 
by a mixing device for gently agitating the contents of one or more 
cylindrical containers. The device includes a plurality of cylindrical 
rollers parallely juxtaposed and adapted to rotate in an eccentric fashion 
about respective longitudinal axes that are parallel to each other but 
inclined to the respective cylindrical axes of the rollers. A drive bar 
coupling interconnects the rollers and a drive motor so that the rollers 
rotate in the same direction and at the same speed thereby imparting a 
simultaneous rocking and rolling motion to the containers when placed in 
supporting contact with adjacent rollers. 
For a better understanding of these and other aspects of the present 
invention, reference may be made to the following detailed description 
taken in conjunction with the accompanying drawing in which like reference 
characters designate like parts throughout the figures thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIGS. 1 through 4, there is shown a mixing device 
according to the present invention as it operates to blend the contents of 
a pair of closed test tubes 11. The mixing device includes a series of 
cylindrical rollers 12a, 12b, 12c, 12d, 12e, and 12f rotatably mounted 
between a front support bracket 14 and a rear support bracket 16 above a 
base plate 18 to which each bracket is securely affixed. The rollers 12a 
through 12f are parallel to each other and juxtaposed so that the test 
tubes 11 or other sealed cylindrical containers, such as vials, may be 
supported between adjacent rollers. Rear bracket 16 is provided with a 
plurality of bearing couplers 20 equidistant from each other and identical 
in number to rollers 12a through 12f. Similar equidistant couplers 22 each 
provided with a bearing 24, better shown in FIG. 7, are rotatably fastened 
to the front support bracket 14 so that a series of longitudinal axes AA, 
BB, CC, DD, EE, and FF, all situated in a plane substantially parallel to 
baseplate 18, are established for rotation of the respective rollers. 
Each of the cylindrical rollers 12a, 12b, 12c, 12d, 12e and 12f is 
similarly adapted at its ends to be fixed along the respective 
longitudinal axes AA, BB, CC, DD, EE, and FF between the couplers 20 and 
22 on the rear and front brackets 16 and 14, respectively. Lying on the 
respective longitudinal axes AA, BB, CC, DD, EE and FF, the points of 
fixed engagement on either end of the rollers 12a through 12f are each 
eccentric with its associated end by an equal radial amount at each end, 
with each point of fixed engagement being angularly displaced relatively 
to one end of the roller by 180.degree. relative to that at the opposite 
end. Thus, as shown for example in FIG. 1, the axis of rotation AA of 
roller 12a is inclined to its cylindrical axis CA so that the roller 
rotates in an eccentric fashion upon couplings 20 and 22. 
An electric motor 26 for driving the mixing device is secured to the 
baseplate 18 via a mounting bracket 28 and is provided with input 
terminals (not shown) to receive a source of electrical power. The motor 
26 is suitably geared internally to provide an output speed of typically 
about 15 R.P.M. to prevent undue movement or sliding of the test tubes 11 
during mixing and is preferably of the bi-directional type that 
automatically reverses its rotational direction upon the encountering of 
an obstruction in the drive system. (It should be noted that the output 
speed provided by motor 26 may be varied dependent upon the requirements 
of any particular mixing application). An output shaft 30 extends from 
electric motor 26 and is secured to a motor crank 32 to provide circular 
motion to a first drive bar 34. A motor crank pin 36 is affixed to the 
motor crank 32 and extends therefrom to engage the first drive bar 34 near 
its center to couple the motor crank 32 to the drive bar 34. A pair of 
drive bar pins 38, better shown in FIG. 7, are located near either end of 
the first drive bar 34 and extend therethrough to engage one end of a pair 
of bell cranks 40 thereby coupling the drive bar 34 to the bell cranks 40 
and providing rotational motion about the other end of the bell cranks 40. 
Referring now additionally to FIGS. 5 through 7, each bell crank 40 is 
securely engaged by one end of a coupling member 42. Each coupling member 
42 is supported on either side of baseplate 18 by a bracket 46 affixed 
thereto and set within a bearing 44 to insure rotational motion thereof. 
An intermediate bell crank 48, positioned 90.degree. out of phase to each 
bell crank 40 on the opposite sides of the support bracket 46, is 
similarly engaged by the other end of coupling member 42 to insure 
transmission of the rotational motion thereto. It should be noted that the 
ends of coupling members 42 are preferably square-shaped to mate in 
corresponding square holes formed in bell cranks 40 and 48 so that the 
rotational motion transmitted therebetween is achieved without slippage. 
A second drive bar 52 similar in length to the first drive bar 34 is 
coupled to each of the intermediate bell cranks 48 to produce circular 
motion of the second drive bar 90.degree. out of phase with the motion of 
the first drive bar 34. A pair of long connecting pins 50 extend through 
and are secured within the second drive bar 52 near each end thereof to 
couple the drive bar to the intermediate bell cranks 48. It is preferred 
that each long connecting pin 50 be knurled along its middle portion to 
insure firm attachment within the second drive bar 52. A series of roller 
cranks 54, are identically oriented in phase with the intermediate bell 
cranks 48, with each roller crank being pivotally coupled at one end 
thereof to the second drive bar 52 along its length so that the roller 
cranks are turned synchronously by the motion of the second drive bar. The 
exterior pair of roller cranks 54 are coupled to the second drive bar 52 
via the long connecting pins 50, while a series of equidistant short 
connecting pins 56 similarly engage the interior group of roller cranks 
54. At the opposite ends thereof, each roller crank 54 is engaged in fixed 
relationship to respective rollers 12a, 12b, 12c, 12d, 12e, and 12f via 
the couplings 22 so that as the roller cranks are turned by the motion of 
the second drive bar 52, the rollers are rotated in their eccentric 
fashion about their respective rotational axes AA, BB, CC, DD, EE, and FF 
in the same sense of direction and at the same speed of rotation. 
Accordingly, rolling is imparted to the test tubes 11 by the synchronous 
rotation of the rollers 12 with which they are frictionally engaged, and 
the test tubes 11 experience a rocking motion in two dimensions by virtue 
of the inclined rotational axes about which the rollers 12 turn. 
It should be noted that a cover (not shown) normally provided to enclose 
the motor 26 and drive bar mechanisms has been omitted from the drawings 
for the sake of clarity. 
Therefore, it is apparent from the foregoing that the disclosed mixing 
device provides an improved apparatus for gently agitating the contents of 
cylindrical containers, such as closed test tubes or vials, by combining 
full axial rotation of the containers with a rocking motion in two 
dimensions which motions thoroughly blend the container contents. 
Furthermore, the disclosed mixing device is economical in construction and 
safe and reliable in performance. 
Obviously, other embodiments and modifications of the present invention 
will readily come to those of ordinary skill in the art having the benefit 
of the teachings presented in the foregoing description and drawings. It 
is therefore understood that various changes in the details, materials, 
steps, and arrangement of parts, which have been described and illustrated 
to explain the nature of the invention, may be made by those skilled in 
the art within the principle and scope of the invention as expressed in 
the appended claims.