Laboratory Mixer

Abstract

A mixer for mixing fluent material contained in test tubes, flasks and like vessels is provided with a resilient surface for receiving the vessel. The surface is then driven eccentrically to agitate the vessel for producing a vortex mixing action in the vessel. Since the surface is resilient, the amount of agitation imparted to the vessel is dependent on the force with which the vessel is pressed against and into the resilient surface.

Description

BACKGROUND OF THE INVENTION

The present invention relates generally to apparatus for mixing fluent material and more specifically to mixers of the type in which a vessel is agitated eccentrically to produce a vortex mixing action. In particular, the mixer of the present invention is intended for use in laboratories and the like to agitate such vessels as test tubes, flasks and similar laboratory vessels.

Such mixers are known in the art, a typical apparatus being illustrated in U.S. Pat. No. 3,061,280. In such mixers, the vessel, usually a test tube, is held in or against a cup-shaped member which is eccentrically driven to agitate the vessel. In some mixers, the amount or degree of agitation can be manually adjusted by changing the throw or rotational speed of the eccentric drive.

With mixers of this type it is not possible to agitate several test tubes at one time or a relatively large vessels such as a flask or a beaker and manual adjustment of the agitation can be difficult when the vessel is being manually held against the eccentrically driven member.

SUMMARY OF THE INVENTION

In the present preferred form of the invention, the mixer is provided with a relatively large resilient top surface supported on three upright wire rod elements which fix the surface against concentric rotation while permitting movement of the surface in a horizontal plane. A dynamic mounting connected beneath the surface drives the resilient top eccentrically, so that any vessel placed on the surface will be agitated. The surface is large enough to accommodate several test tubes or a flask manually held against the surface. No manual means are provided for changing the throw of the eccentric drive. Instead, the degree of agitation transmitted to a vessel depends upon the force with which the vessel is held against the resilient surface.

OBJECTS OF THE INVENTION

One object of the present invention is to provide a mixer for laboratory use which is capable of simultaneously accommodating a plurality of test tubes or like vessels.

Another object is to provide a vortex laboratory mixer having a relatively large eccentrically driven surface against which vessels, such as Erlenmeyer flasks and the like, can be manually held for vortex mixing the fluent contents of the vessel.

A further object is to provide a vortex mixer for laboratory use wherein the eccentrically driven surface against which the vessels are held for mixing is made of a resilient material so that the degree of agitation imparted to the vessel depends upon the force with which the vessel is pressed against and into the resilient surface.

These and other objects, advantages and characterizing features of the present invention will become more apparent upon consideration of the following detailed description thereof when taken in connection with the accompaning drawings depicting the same.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the mixer of the present invention; and

FIG. 2 is a side elevation view of the mixer partly broken away and in section.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, FIG. 1 shows a mixer of the present invention generally indicated at 10. The mixer includes a base housing 12, an oscillating plate 14 and a pad member 16 adhesively attached to the plate. The top of the housing also has a push on-push off switch 18 for starting and stopping the oscillation of plate 14.

FIG. 2 shows that plate 14 is supported on the upper ends 20 of a plurality, typically three, of spring wire rod members 22. These members extend down into base housing 12 through enlarged openings 24. Housing 12 has its base plate 26 provided with openings 28 which receive the lower ends 30 of the rods. With this arrangement oscillating plate 14 is resiliently supported above base housing 12 for oscillating movement in a generally horizontal plane.

Disposed within housing 12 and supported on the base plate is an electric drive motor 32. The motor is eccentrically connected to oscillating plate 14 by a eccentric coupling member 36. In this respect, motor 32 has its drive shaft 34 fixed to member 36. Also fixed to member 36 in an opening 38 eccentrically positioned with respect to shaft 34 is a second drive shaft 40. Any suitable means such as set screws 42 can be used to fix shafts 34 and 40 to member 36.

Second shaft 40 extends upwardly into a bearing 44 which is fixed in a central opening 46 through oscillating plate 14. With this arrangement rotation of shaft 34 and eccentric member 36 will rotate shaft 40 in a concentric circle about shaft 34. This drives oscillating plate 14 but because the plate is fixed by rods 22 against concentric rotation, plate 14 will simply oscillate to shake or agitate any vessel placed on the surface of pad member 16.

Formed integral with eccentric 36 on the far side of shaft 34 from shaft 40 is a counterbalance portion 43. This counterbalance provides dynamic stability as the eccentric is being rotated to minimize vibration and "walking" of the apparatus.

In operation, switch 18 is pushed to start motor 32, the motor receiving electrical power through a line cord, a portion of which is shown at 48. The operation of motor 32 rotates shaft 34 and the eccentric drive. The rotation of eccentric 36 acting through pin 40 will in turn shake drive plate 14 wherein spring wire rod members 22 prevent plate 14 from rotating but permit the plate to oscillate back and forth and side to side. The motion of plate 14 is transmitted through resilient pad 16 to any test tube flask or like vessel 52 which is placed on and held against the pad. In this way, the fluent material within such a vessel is agitated and mixed.

It is preferred that pad 16 be made of a highly resilient material such as a closed cell foamed neoprene. If such a highly resilient material is used for pad 16, the amount of agitation transferred to the vessel can be controlled by the force with which the vessel is pressed against and into the resilient pad. In this respect, the greater the force with which the vessels is pressed into resilient pad 16, the more friction between the vessel and pad and the more compacted and firm will be the area indicated at 50 beneath and around the vessel. This permits a greater degree of agitation when the vessel is pressed hard against resilient pad 16 and a lesser degree of agitation when the vessel is only lightly pressed against the surface. Thus, in the present invention, the degree of agitation can be changed quickly and easily simply by changing the pressure with which vessel 52 is manually held against and pressed into resilient pad 16.

In order to protect bearing 44 and prevent resilient pad 16 from being pressed into opening 46 when a vessel is held against the pad, a cover 54 is adhesively attached over the opening.

Having thus described the invention in detail, it should be appreciated that the present invention accomplishes its intended objects in providing a mixer of the vortex mixing type which is suitable laboratory use. The relatively large oscillating surface provided by pad 16 can accommodate a variety of laboratory vessels such as test tubes and flasks. Furthermore, since the vessels are all manually held on pad 16, it would be possible for the operator to hold a plurality of test tubes in his hand and simultaneously press them all against pad 16. A further accomplishment of the present invention is that there is no need for means to mechanically adjust the amount of agitation since the degree of agitation can be changed simply by changing the force with which the vessel is pressed against and into resilient pad 16.

Claims

Having thus described the invention, what is claimed as new is:

1. In a laboratory mixer having a base, a plate supported above the base and an eccentric drive means mounted on the base and operatively connected to the plate to shake the plate, the improvement comprising a substantially flat resilient foamed rubber pad fixed to the upper surface of said plate to receive thereon a vessel to be agitated, the degree of agitation imparted to said vessel being determined solely by the force with which said vessel is pressed against said pad.

2. A laboratory mixer as in claim 1 including at least three spring wire rods upstanding from said base, said plate being supported on the upper ends of said rods, said rods preventing rotation of said plate while permiting said plate to vibrate responsive to operation of said eccentric drive means.

3. A laboratory mixer comprising:

a. a base;

b. at least three spring wire rods upstanding from said base;

c. a plate supported on the upstanding ends of said rods;

d. motor means mounted on said base;

e. eccentric means operatively connected to said plate to shake said plate when driven by said motor means; and

f. vessel contact means including a substantially flat pad of resilient material fixed to said plate and adapted to transfer the eccentric motion of said plate to a vessel manually pressed against said pad, the degree of agitation imparted to said vessel by said resilient pad being dependent upon the force with which said vessel is made to frictionally engage and compress said pad.

4. A laboratory mixer as in claim 3 wherein said substantially flat resilient pad is made of closed cell foamed neoprene.

5. A laboratory mixer as in claim 3 including a housing enclosing said motor and a major portion of said spring wire rods, there being openings in the top of said housing to permit passage of the upper ends of said rods so that said plate is supported above the top of said housing.