Claims
- 1. In a pipetting assembly of the type wherein a plunger reciprocates into and out of a chamber in a pipette body to displace air through a passageway to a detachable pipetting tip, the improvement comprising:
- tip attachment means including a shell slidably disposed around said pipette body and including a plurality of spring biased flexible fingers having hooks for gripping said pipetting tip; and
- annular tip sealing means disposed around said passageway at a lower end of said pipette body.
- 2. The invention of claim 1 wherein said pipetting tip is in the shape of a hollow cone having an aperture at its apex, an open base with a planar rim, and a circumferential triangular lip having one side contiguous with the outside of said cone.
- 3. The invention of claim 2 wherein said hooks engage said lip.
- 4. The invention of claim 3 including annular notch and ridge surfaces in said pipette body and on said fingers, respectively, whereby reciprocation of said shell relative to said pipette body causes said fingers to spread away from said detachable pipetting tip.
- 5. The invention of claim 4 including key ring means attached to said plunger whereby reciprocation of said plunger into said chamber past a shell-unlocked point causes said fingers to spread.
- 6. The invention of claim 5 further including a shaft locking mechanism actuated by an inner shaft plunger reciprocating along its axis to lock a coaxial middle shaft body relative to a coaxial outer shaft shell, said mechanism comprising:
- a pair of semicircular sections disposed around said inner shaft and inside said middle shaft, said sections terminating in hinge means between said sections, each said section having on its radially outer side at least one protuberance which impinges upon said middle shaft preventing said sections from unfolding completely into a single plane;
- said middle shaft having flexible locking means, including recesses complementary to said protuberances, to hold said outer shaft by static friction when force is applied to said locking means by said protuberances;
- hinge opening means extending radially from said inner shaft which, upon reciprocation of said inner shaft, apply pressure tending to open said hinge means causing said sections to flatten relative to each other and said protuberances to push said recesses outward to lock said middle shaft against said outer shaft.
- 7. The combination of claim 6 wherein said hinge opening means includes a cam which bears against said hinge.
- 8. The combination of claim 6 wherein said sections each include a crank extending approximately parallel to said axis from the middle of a planar side of said section, and also includes tension spring means to pull said cranks together, and wherein said hinge opening means includes a cam which upon reciprocation of said shaft wedges between and forces apart said cranks thus forcing said hinge to open reducing the angle supplementary to the angle between said sections and increasing their outside diameter to force said protuberances against said locking means.
- 9. The combination of claim 6 wherein said sections terminate at opposite ends in a ball joint and in a corresponding socket joint, and said hinge means is formed from said ball and socket joints.
- 10. The invention of claim 4 wherein the thickness of said fingers increases with increasing distance from said hooks.
- 11. The invention of claim 4 wherein said shell is manually reciprocated independently of reciprocation of said plunger.
- 12. The invention of claim 2 wherein said detachable tip has a flat gasket disposed on said rim.
- 13. The invention of claim 1 wherein said tip sealing means comprises a gasket.
- 14. A shaft locking mechanism actuated by an inner shaft reciprocating along its axis to lock a coaxial middle shaft relative to a coaxial outer shaft, said mechanism comprising;
- a pair of semicircular sections disposed around said inner shaft and inside said middle shaft, said sections terminating in hinge means between said sections, each said section having on its radially outer side at least one protuberance which impinges upon said middle shaft preventing said sections from unfolding completely into a single plane;
- said middle shaft having flexible locking means, including recesses complementary to said protuberances, to hold said outer shaft by static friction when force is applied to said locking means by said protuberances;
- hinge opening means extending radially from said inner shaft which, upon reciprocation of said inner shaft, apply pressure tending to open said hinge means causing said sections to flatten relative to each other and said protuberances to push said recesses outward to lock said middle shaft against said outer shaft.
- 15. In a pipetting assembly of the type wherein a plunger reciprocates into and outer of a chamber in a pipette body to displace air through a passageway to a detachable pipetting tip, and having tip attachment means including a shell slidably disposed around said pipette body, said shell having a plurality of spring biased flexible fingers with engaging hooks for gripping said pipetting tip to said pipette body, the improvement comprising:
- a detachable pipetting tip having the shape of a hollow cone with an open base seatable around said passageway and an aperture at the cone apex for discharging fluids from said pipetting assembly;
- said open base having a conformably configured seating rim for forming a seal around said passageway, and having a circumferential annulus engageable by said hooks whereby said rim is held in sealing relation around said passageway.
- 16. The invention of claim 15 wherein said annulus is disposed on the outside of said cone for gripping by said hooks.
- 17. In a pipetting assembly wherein a plunger reciprocates into and out of a chamber in a pipette body to displace air through a passageway to a detachable pipetting tip and wherein said assembly includes tip attachment means including inner and outer relatively slidable cylindrical members, said members including means adjacent said passageway for gripping said detachable pipetting tip, the improvement comprising:
- a locking member for inhibiting relative sliding movement of said cylindrical members to lock said detachable pipetting tip around said passageway,
- said inner cylindrical member including at least one biasable wall section movable between an unbiased first position wherein said cylindrical members are free to move with respect to each other, and a biased second position where said biasable wall section is in frictional contact with said outer member; and
- lever means responsive to movement of said plunger to engage said biasable wall section to lock and unlock said cylindrical members relative to each other.
- 18. In a pipetting assembly of the type wherein a slidable cylindrical shell having tip gripping fingers surrounds a cylindrical pipette body and said shell slides between a tip-gripped position wherein said fingers grip a detachable tip against said pipette body and a tip-released position where said fingers are disengaged from said tip, lock means comprising:
- a flexible portion in said pipette body; and
- lever means having a first end disposed to be swung between a shell-locked position where said lever is relatively perpendicular to, and forces said flexible portion against, said shell to lock said shell by static friction, and a shell-unlocked position where said lever is relatively less perpendicular to, and does not force said flexible portion against, said shell.
- 19. A pipetting assembly of the type and as in claim 18 wherein said cylindrical pipette body includes along its central axis a reciprocating center shaft which moves relative to said body from a point where said shaft causes said lever to be in said shell-locked position, to a point where said shaft causes said lever to be in said shell-unlocked position.
- 20. A pipetting assembly as in claim 19 wherein said lever means is at least one semicircular section disposed around said center shaft and inside said inner shaft, and said semicircular section includes a crank extending approximately perpendicularly to said center shaft from the middle of a planar side of said section.
- 21. The combination of: a pipette body defining a chamber and having a plunger which reciprocates into and out of said chamber, a passageway communicating between said chamber and an outlet from said body; a detachable pipetting tip, tip attachment means including a slidable shell disposed around said pipette body and including a plurality of spring biased flexible fingers having means for latching said detachable tip and holding said tip in sealing relation around said passageway outlet, said slidable shell including locking means for locking said shell from sliding movement relative to said pipette body and to secure said detachable tip around said outlet, said locking means releasable to release said detachable tip in response to movement of said plunger.
- 22. A detachable pipetting tip substantially in the shape of a hollow cone having an aperture at its apex, an open base with a planar seating rim to be engaged with a gasket, said rim adjacent the interior surface of said tip, and a circumferential lip adjacent said rim, said lip formed at the base end of said cone shaped pipetting tip by first extending the outer surface of the tip out from the rim at an acute angle to the plane containing said open base and rim a distance external to where the exterior surface would be if the tip were shaped precisely like a hollow cone and thereafter extending the outer surface at a different angle back to where the exterior surface would be for the exterior surface of said precisely shaped hollow cone, the orientation of both said angles being such that the termination locus of each extension is located between parallel planes containing respectively the base and apex, the originating position of the first extension being in the base plane, said lip thereby engageable for securement of said tip to a pipette body.
- 23. In a pipetting assembly wherein a plunger reciprocates within a chamber along an axis of a pipette body to displace fluid through a passageway in fluid communication with the interior of a detachable pipetting tip means having a first end proximal to said pipette body and an aperture at a second end distal from said pipeette body, the improvement comprising:
- tip attachment means associated with said pipette body having a radially movable tip locking surface; and
- a lip on the exterior of said detachable pipetting tip means having a locking surface;
- said tip means being attachable by axial movement to engage said tip attachment means so that said first end of said tip means abuts said pipette body, whereby said tip attachment means snap locks with said tip means in that said tip locking surface of said tip attachment means initially moves radially away from said axis and thereafter radially toward said axis for engaging said locking surface of said lip of said tip means.
- 24. The pipetting assembly of claim 23 wherein said first end of said detachable pipetting tip means has a rim, and further comprising a gasket interposed between said pipette body and said rim, said rim bearing against said gasket upon attachment of said tip means to form an air-tight seal between said tip means and pipette body.
- 25. The pipetting assembly of claim 23 wherein said tip attachment means has a funnel surface and said detachable pipetting tip means has a lip surface complementary to said funnel surface, said lip surface engaging said funnel surface so that said tip locking surface is moved radially outwardly when said tip means is moved axially into contact with said tip attachment means.
- 26. A detachable pipetting tip means having a first end to be engaged with a pipette body and an aperture at a second end distal from said pipette body, a chamber being located interior of said pipette body along an axis of said pipette body wherein a plunger reciprocates to displace fluid through a passageway in fluid communication with the interior of said detachable pipetting tip means when said detachable pipetting tip means is attached to said pipette body by tip attachment means associated with said pipette body having a radially movable tip locking surface, comprising:
- a lip on the exterior of said detachable pipetting tip means having a locking surface;
- said tip means being attachable by axial movement of said tip means to engage said tip attachment means so that said first end of said tip means abuts said pipette body, whereby said tip attachment means snap locks with said tip means in that said tip locking surface of said tip attachment means initially moves radially away from said axis and thereafter radially toward said axis for engaging said locking surface of said lip of said tip means.
Parent Case Info
This is a continuation of application Ser. No. 06/501,585, filed June 6, 1983, now abandoned.
US Referenced Citations (12)
Continuations (1)
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Number |
Date |
Country |
Parent |
501585 |
Jun 1983 |
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