Self-balancing centrifuge method and apparatus

Claim 3

The method as claimed in claim 1 wherein the centrifuge is mounted as an inverted pendulum.

Claim 4

A method as claimed in claim 1 wherein the force of the springs biasing the centrifuge to a substantially vertical axis position is selected to provide a natural vibration frequency of the centrifuge corresponding to a centrifuge speed which is less than ten percent of the normal full operating speed of the centrifuge.

Claim 5

A self-balancing centrifuge comprising a rotatable shaft, means for supporting said shaft while permitting pivotal displacement thereof about a pivot point at the center line of said shaft, said supporting means including spring biasing means arranged to bias said shaft towards a substantially vertical position about said pivot point, a motor connected to rotate said shaft, a centrifuge wheel mounted upon said shaft at an axial position thereon substantially displaced from said pivot point, said centrifuge wheel including a plurality of cups pivotally connected to the periphery of said wheel for receiving sample containers of liquid to be separated by the centrifuge action, said wheel defining an annular chamber arranged concentrically about said shaft, a counterbalance mass partially filling said annular chamber, said counterbalance mass being arranged to shift in its angular position within said annular chamber to automatically balance said wheel for unequal loading of said cups at speeds above the natural vibration frequency of the combination of said shaft and said wheel about said pivot point, said annular chamber being formed to allow the shift of said counterbalance mass to a position which is at substantially the same level as said cups during rotation of said centrifuge wheel.

Claim 6

A self-balancing centrifuge comprising a rotatable shaft, means for supporting said shaft while permitting pivotal displacement thereof about a pivot point at the center line of said shaft, said supporting means including spring biasing means arranged to bias said shaft towards a substantially vertical position about said pivot point, a motor connected to rotate said shaft, a centrifuge wheel mounted upon said shaft at an axial position thereon substantially displaced from said pivot point, said centrifuge wheel including a plurality of cups pivotally connected to the periphery of said wheel for receiving sample containers of liquid to be separated by the centrifuge action, said wheel defining an annular chamber arranged concentrically about said shaft, a counterbalance mass partially filling said annular chamber, said counterbalance mass being arranged to shift in its angular position within said annular chamber to automatically balance said wheel for unequal loading of said cups at speeds above the natural vibration frequency of the combination of said shaft and said wheel about said pivot point, said annular chamber being formed to allow the shift of said counterbalance mass to a position which is at substantially the same level as said cups during rotation of said centrifuge wheel.

Claim 7

A centrifuge as claimed in claim 4 wherein said counterbalance mass comprises a plurality of solid bodies.

Claim 8

A centrifuge as claimed in claim 5 wherein each of said solid bodies has a circular profile when viewed form above.

Claim 9

A centrifuge as claimed in claim 4 wherein said supporting means includes means for maintaining a substantially fixed vertical position for said shaft while permitting restrained pivotal deflections thereof away from the vertical alignment position.

Claim 10

A centrifuge as claimed in claim 7 wherein said means for maintaining a substAntially fixed vertical position comprises a ball swivel bearing centered at said pivot point.

Claim 11

A centrifuge as claimed in claim 4 wherein the combination of said shaft and said wheel is supported as an inverted pendulum with said pivot point positioned beneath said wheel.

Claim 12

A centrifuge as claimed in claim 4 wherein said natural vibration frequency corresponds to a centrifuge speed which is less than ten percent of the normal full operating speed of the centrifuge.

Claim 13

A centrifuge as claimed in claim 8 wherein said supporting means comprises a fixed supporting base mounting and supporting said ball swivel bearing, a mounting plate axially spaced away from said supporting base, said mounting plate being fixed with respect to the axial position of said shaft, and said spring biasing means comprising compression springs arranged between said supporting base member and said plate and spring biasing said plate to a position substantially parallel to said base member.

Claim 14

A centrifuge as claimed in claim 11 wherein said drive motor is mounted upon said mounting plate with its shaft extending vertically upward on an axis passing through said pivot point, said rotatable shaft being connected to and forming an extension of the shaft of said drive motor and being supported upon and directly driven thereby.

Claim 15

A centrifuge as claimed in claim 4, wherein said centrifuge wheel comprises a light weight removable sample tray including the peripheral portions of said wheel and the cups for receiving sample containers and a portion defining said annular chamber, the sample tray portion of said wheel being removable from said annular chamber portion for the purpose of transferring the sample containers as a group for processing in another apparatus.

Claim 16

A centrifuge as claimed in claim 4 wherein there is provided energy absorption means responsive to displacement movements of said shaft away from the vertical position to absorb the vibration energy of the combination of said shaft and said wheel to thereby limit the vibration amplitudes at low frequencies.

Claim 17

A centrifuge as claimed in claim 14 wherein said energy absorption means comprises a plurality of hydraulic shock absorber devices.

Claim 18

A centrifuge as claimed in claim 4 wherein said spring biasing means includes snubber springs operable when the vibration excursion exceeds a predetermined amplitude to increase the spring rate and to thereby limit further vibration amplitude excursion to prevent damage to the apparatus.

Claim 19

A centrifuge as claimed in claim 5 wherein the configuration of each of said solid bodies is such as to require sliding movement upon the lower surface of said chamber for the shift in position to achieve balance.

Claim 20

A centrifuge as claimed in claim 17 wherein at least one of said lower surface of said chamber and the surface of each of said bodies in engagement therewith consist of a non-skid surface.