Centrifuge Chuck For Disposable, Snap-in Centrifuge Rotor

Abstract

A chuck suitable for holding a disposable centrifuge rotor during centrifuging and requiring only minimum skill to place in position. Once the rotor is snapped into position on the chuck it is held by an elastomeric gripping member. The base of the rotor is designed to effect this holding. In removing the rotor, only a manual tipping action involving a modest horizontal force near the top of the rotor is required. The chuck is simple and inexpensive; and it does not require any great deal of technical skill to operate.

Description

This invention relates to centrifuges and more particularly to a unique combination of a chuck and a snap-in disposable centrifuge rotor for attachment thereto.

In centrifuging liquids such as blood, there is a need for a simple chuck which can hold the centrifuge rotor in proper alignment and which provides rapid and reliable engagement and disengagement with the rotor. In processing blood, the technician who performs the processing steps should be as free as possible from engineering details. This, in turn, means that he should be able to place a centrifuge rotor in a chuck to attain automatic registry both with respect to axial alignment and perpendicular alignment and to effect the locking of the rotor in the chuck with the minimum number of simple motions.

The disposable rotor of this invention is of an upwardly tapering, bell-shaped configuration which is not adapted for manual gripping to lift it out of a standard O-ring form of chuck. A mechanical ejection system chuck such as described in U.S. Pat. No. 3,581.981, provides a technically acceptable way of extracting the bowl from the chuck. However, for some large-scale use application, this type of chuck is too expensive.

It is therefore a primary object of this invention to provide a simple, easily used chuck-rotor combination for use in a centrifuge. It is another object of the invention to provide a chuck-rotor combination of the character described which is particularly useful in centrifuges used to process blood and which requires only simple operations to lock or unlock the centrifuge rotor into the chuck, these operations involving only a snapping in of the rotor and in one embodiment the additional step of the tightening of three bolts. It is yet another object to provide an inexpensive chuck which is particularly usable for one-use centrifuge rotors. Other objects of the invention will in part be obvious and will in part be apparent hereinafter.

In the chuck-rotor combination of this invention, the chuck is formed of an upper clamp ring and a lower chuck body on which the rotor fits for automatic axial and perpendicular alignment. The upper clamp ring and lower chuck body are configured to define between them a groove adapted to hold an elastomeric gripping member, and they may be formed as one integral part or as two separate components adapted to be locked together by screws. The base of the rotor is designed to provide an upwardly inclined shoulder over which the elastomeric gripping member fits in gripping engagement. In the embodiment in which the chuck is formed of two lockable components when the screws which lock the chuck members are turned about one full turn to loosen the chuck members the rotor may be snapped into place in the chuck. Once the rotor is snapped into place, the screws are tightened and the centrifuge is in operational condition. Removal of the rotor is accomplished with similar ease. In an alternative embodiment wherein the chuck is formed as a single component the rotor is installed with a firm, downward force normally applied with both hands and may be removed with the aid of a simple tool.

The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings in which

FIG. 1 is a vertical cross section of the chuck and rotor of an embodiment of this invention in which the chuck is formed of two separate components;

FIG. 2 is a bottom view of the chuck of FIG. 1 showing the position of the locking screws;

FIG. 3 is an enlarged detailed cross section showing the configurations of the chuck of FIG. 1, the centrifuge rotor base, the elastomeric gripping ring and a locking screw in the unlocked position;

FIG. 4 is an enlarged detailed cross section as in FIG. 3 showing the rotor and chuck in the locking position; and

FIG. 5 is an enlarged detailed cross section of one portion of the chuck and rotor of an embodiment in which the chuck is formed as a single component and the gripping member is of a unique configuration.

In FIG. 1 the chuck and gripping member are shown in cross section and the rotor in partial cross section. Except for the design of the external configuration of the base of the rotor which is critical to this invention, the rotor shown is similar in internal construction and operation to that described in U.S. Pat. No. 3,145,713 (see particularly FIG. 6 of that patent). For this reason, no detailed description of the internal design of the rotor is required, only the basic flow pattern being illustrated.

The rotor 10 is mounted in chuck 11 through elastomeric gripping member 12. The chuck in the embodiment of FIG. 1 is formed of an upper clamp means formed as ring 13 and a lower chuck body 14, the latter being adapted for attachment to a rotatable spindle 15 such as the temperature-controlled spindle described in U.S. Pat. No. 3,604,769. The upper and lower chuck members are locked by at least three locking members 16 (See also FIG. 2).

The rotor 10, which may be a one-use disposable rotor, is designed to be attached through a stationary external connection 20 to a source of liquid (e.g., blood) to be centrifuged through inlet tube 21, and to a storage container for the centrifugate (e.g., blood plasma) through discharge tube 22. The stationary inlet tube 20 is in fluid communication with a stationary feed tube 23 extending into the rotor. Rotary seals such as described in U.S. Pat. Nos. 3,409,213 and 3,565,330 provide the necessary contamination-free sealing between the stationary components and the rotating rotor 10. A baffle system such as that shown in FIG. 1 to be made up of baffle plates 24 and 25 direct the liquid flow and permit the centrifuged solids (e.g., blood red cells) to be collected in the centrifuge rotor.

The rotor housing is formed as a tapered bell-shaped section 30 and a bottom member 31 which is joined to the bell-shaped section to form, with a rotary seal (not shown) a fluid-tight enclosure within the housing. The bottom member is formed from its center outwardly to have a central circular alignment surface 32, an upwardly inclined surface 33 forming a major portion of the bottom member and a flat peripheral surface 34.

As will be seen in the enlarged cross sectional detail of FIG. 3, the outer lower periphery of the base of the bell-shaped section is configured to define an inclined shoulder 35 the angle of inclination .theta. of which approximates 45.degree.that is it is 45.degree..+-. 15.degree.. The shoulder 35 is formed between a lower wall section, consisting of a slightly inclined wall 36 and a vertical wall 37, and upper vertical wall section 38. Th angle .phi. defined between wall 36 and the vertical ranges between 15.degree. and 30.degree. and the height of vertical wall 37, which represents the maximum diameter of the rotor base will normally be about 0.03 inch. Although wall 36 may also be vertical, a preferred construction is to provide a "lead" on the rim of the base to make insertion of the bowl easier. The importance of shoulder 35 and its location will be made apparent in the discussion which follows.

Returning to FIG. 1, it will be seen that the upper surface of chuck body 14 is configured, from its center outwardly, to have a shallow central well 40 sized to correspond in diameter to the diameter of the central circular alignment surface 32 of the rotor, an upwardly inclined surface 41 corresponding to, but spaced from, the upwardly inclined surface 33 of the rotor and a flat annular surface 42 corresponding to the flat peripheral surface 34 of the rotor. The engagement of the flat peripheral surfaces 34 and 42 and of the central circular alignment surface 32 of the rotor within the shallow central well 40 automatically provides both perpendicular and axial alignment of the rotor in the chuck body. The chuck is mounted on spindle 15 through collar 43 by suitable means such as by use of an adhesive along with a close cylindrical fit.

As will be seen more clearly in FIGS. 3 and 4, the lower chuck body 14 has an outer flat peripheral surface 44 somewhat lower than the flat annular surface 42. An upwardly extending annular ring 45 joins flat annular surfaces 42 and 44. The upper surface 46 of ring 45 serves as one side of groove 47 which is adapted to contain elastomeric gripping member in the form of an O-ring 12. The inner surface 48 of ring 45 is of a diameter which permits engagement with the vertical wall 37 of the lower wall section of the rotor base with preferably about an 0.010 inch clearance. This clearance can range between about 0.008 and 0.015 inch.

Preferably the lower edge of gripping shoulder 35 of the rotor base is between about 0.1 and 0.2 inch above the perpendiculant register, i.e., annular surface 42, for a rotor which has a diameter ranging between about 4.0 and 5.5 inches in diameter measured at the vertical wall 37 of the lower section of the rotor base. Thus the ratio of rotor base edge height, as measured along the bottom edge of shoulder 35, above the perpendiculant register to the outside diameter of the rotor base may range between about 0.1/5.5 to 0.2/4.0 or about 0.02 to 0.05. Another relationship which may be used to define the configuration of the rotor base and the gripping means is the ratio of rotor base edge height (distance from surface 42 to the bottom edge of wall 37) to shoulder edge height (distance from surface 42 to the bottom edge of shoulder 35). This ratio should be between about 0.2 and 0.6.

The upper chuck clamp ring 13 will be seen in FIGS. 3 and 4 to have an internal surface which is machined to define a lower vertical wall section 51 and an upper vertical wall section 52 of small diameter. These wall sections are joined by shoulder 53. The lower vertical wall section 51 is aligned with the outer surface of ring 45 for engagement herewith. The upper portion of wall member groove 47, the depth of which is controllable to alter the cross sectional configuration of the O-ring to cause it to loosen or grip the rotor as seen in FIGS. 3 and 4, respectively.

Each of the chuck locking means 16 are conveniently formed of a clamp screw 55 which is internally threaded to engage the threads of a button-headed screw 56.

When the rotor is to be installed in the chuck the locking means are loosened by turning clamp screw 55 by about one turn to place the chuck clamp ring and chuck body in the relative positions shown in FIG. 3. The rotor is gripped manually around its top and is then thrust firmly downwardly to become engaged in the position shown in FIG. 3. It will be seen that all that is involved is the insertion of the gripping shoulder 35 under a small portion of O-ring 12. Rotor alingment in the chuck is automatically achieved. Then the locking means are tightened by turning screws 55 by about one full turn. As will be seen in FIG. 4, the downward movement of clamp ring 13 forces the O-ring to engage and tightly grip the rotor shoulder 35. The rotor is thus firmly held in the chuck when the chuck is rotated. When the chuck is stopped, the chuck clamp ring is raised by turning screws 55 and the rotor is removed by subjecting it to a tipping action.

FIG. 5 illustrates in fragmented cross section a second embodiment of the chuck and gripping means wherein the lower chuck body means and the upper chuck ring means are formed as one integral component, thus eliminating the need for any chuck locking means such as the clamp screw 55 and buttonheaded screw 56 of FIGS. 3 and 4. In FIG. 5 like reference numerals are used to refer to like components in FIGS. 3 and 4.

The chuck 11 of the apparatus of FIG. 5 is formed of a single metal piece 60 which provides the required lower chuck body 61 and upper chuck ring 62. It is, of course, within the scope of this invention to form these elements as separate components and fasten them together by some appropriate means such as screws. However, this will normally not be the preferred construction. The groove 63, wherein the elastomeric gripping ring 64 is held, is machined into the internal surface 65 of chuck ring 62. The gripping member 64 is an annular elastomeric member cut to set in groove 63 and to make a tight fit with lower vertical wall 37 and shoulder 35 of the rotor bottom. Thus the cross section of gripping member 64 may be described as rectangular with a triangular extension 66 integral with the inner top portion, the lower exposed surface 67 of the triangle being adapted to make a tight fit with shoulder 35 of the rotor base.

A comparison with gripping ring 12 of FIGS. 3 and 4, will show that the uniquely configured locking member 64 of FIG. 5 serves the identical purpose of gripping ring 12 and in the same manner. The apparatus of FIG. 5 has the advantage of the operator's being able to insert and withdraw the rotor without having to screw and unscrew any locking means. Insertion of the rotor is accomplished by forcing it into locking position (FIG. 5) with a firm force applied directly downwardly. Removal of the rotor is accomplished by using the tool 70 which is in effect a rubber coated lever 71 attached to a handle 72. The lever 71 is used to apply force to centrifuge housing 30, using the internal wall of the protective housing 73, which is placed around the centrifuge, as s rigid support against which lever 71 is rested. A slight angular movement of handle 72 of the tool serves to pry a portion of the shoulder 35 free from its corresponding engaging surface of gripping member 64. This is sufficient to free the entire rotor from the chuck.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description are efficiently attained and, since certain changes may be made in above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

I claim:

1. In a centrifuge in which a rotor is held for high-speed rotation in a chuck mounted on a rotatable spindle, the combination of a rotor and a chuck adapted for quick engagement with said rotor through gripping means, said chuck comprising in combination

a. lower chuck body means configured on its upper surface to comprise, from its center outwardly, a central shallow well providing an engageable wall, an upwardly inclined surface, a first flat annular surface, and an upwardly extending wall having an internal surface and an essentially flat second annular surface;

b. upper chuck ring means providing an angled internal surface,

c. a groove defined by said second annular surface of said lower chuck body means and said angled internal surface of said upper chuck ring means; said rotor comprising

d. a bottom member configured on its surface to comprise, from its center outwardly, a central circular alignment surface engaging said wall of said central shallow well of said chuck, an upwardly inclined surface essentially corresponding in area to said inclined surface of said lower chuck body means and spaced therefrom, and a peripheral flat annular surface engaging said first flat annular surface of said lower chuck body means, and

e. rotor housing means joined to said bottom member and forming therewith a rotor base configured from the bottom up to have an outwardly inclined section, a lower vertical gripping section representing the maximum diameter of said rotor base and just clearing said internal surface of said upwardly extending wall of said lower chuck body means, an inwardly inclined gripping shoulder and an upper vertical section; forcing

f. and gripping means comprising an elastomeric gripping ring held within said groove in said chuck in combination with locking means forcing said lower vertical gripping section and said inwardly inclined gripping shoulder of said rotor base into engagement with said gripping ring thereby to lock said rotor to said chuck through said gripping means.

2. A centrifuge in accordance with claim 1 wherein the angle defined between said outwardly inclined section of said rotor base and said internal surface of said upwardly extending wall of said lower chuck body means ranges between about 15.degree. and 30.degree..

3. A centrifuge in accordance with claim 1 wherein the clearance between said lower vertical gripping section of said rotor base and said internal surface of said upwardly extending wall of said lower chuck body means ranges between about 0.008 and 0.015 inch.

4. A centrifuge in accordance with claim 1 wherein the ratio of the height of said rotor base, measured from said first flat annular surface of said lower chuck body means to the lower edge of said shoulder, to the outside diameter of said lower vertical gripping section of said rotor base ranges between about 0.02 and 0.05.

5. A centrifuge in accordance with claim 1 wherein the ratio of the height of said rotor base, measured from said first flat annular surface of said lower chuck body means to the lower edge of said lower vertical gripping section, to the height of said shoulder, measured from said first flat annular surface to the lower edge of said shoulder, ranges between about 0.2 and 0.6.

6. A centrifuge in accordance with claim 1 wherein said lower chuck body means is separate from said upper chuck ring means and includes a flat peripheral surface which surrounds said upwardly extending wall and is lower than said first flat annular surface; wherein said angled internal surface of said upper chuck ring means is defined by a lower vertical wall section, and an upper vertical wall section joined thereto through a shoulder, whereby a portion of said lower vertical wall section engages an external surface of said upwardly extending wall and with said shoulder forms said groove, and wherein said locking means comprises screw means to force said upper chuck ring means toward said lower chuck body means thereby to force said elastomeric gripping ring and said rotor base into engagement.

7. A centrifuge in accordance with claim 1 wherein said lower chuck body means and said upper chuck ring means are a single component and said gripping ring has a generally rectangular cross section with an upper inner integral triangular extension the lower exposed surface of which is adapted to make a tight fit with said inclined shoulder of said rotor base thereby to provide said locking means integral with said gripping ring to form said gripping means.

8. A centrifuge in accordance with claim 1 wherein the angle of inclination of said inclined shoulder of the base of said rotor housing is about 45.degree..